No abstract

A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP). The alloy contains a low volume fraction ofα-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared with those of the nonpressed alloy. ECAP leads to an intensive grain refinement accompanied by an increased dislocation density. All electrochemical tests confirm that corrosion resistance of the alloy remarkably diminished with increasing the ECAP number of passes. This is presumably due to the breakdown of theα-AlFeSi after ECAP leading to higher number of galvanic cells and enhanced dissolution of the aluminum matrix.

No abstract

We report on the carrier doping effect (achieved through La doping) on the electronic structure, crystalline structure, grain morphology, and electric and magnetic properties of the ferromagnetic perovskite Sr2FeMoO6. X-ray diffraction on Sr2−xLaxFeMoO6 (x=0, 0.25, 0.5, and 1) ceramic powders shows that all compounds have the tetragonal crystal structure with I4∕mmm symmetry. The cell parameter a and the volume of the tetragonal structure increase with the La doping and the grain size is halved with respect to that of undoped Sr2FeMoO6. Mössbauer spectroscopy shows that the presence of La reduces the degree of ordering on the Fe and Mo sites which causes a reduction of the saturation magnetization MS. However, the addition of electrons in the system results in an increase of the Curie temperature of the Sr2FeMoO6. All these results are supported by ab initio calculations which indicate that the half-metallic character is preserved upon doping and that the magnetization decreases for perfect samples by 1μB∕La atom in a formula unit.

No abstract